Top nozzle removal and replacement fixture and method in a reconstitutable fuel assembly

摘要

A fixture for removing a top nozzle of a reconstitutable fuel assembly held in a fixed position within a work station includes a pair of guide openings in two diagonally opposed corners of its base to movably mount the base on a pair of upstanding guide members of the work station and on the top nozzle in alignment therewith. Also, the fixture includes a pair of hollow expandable split sleeves with wedge pins inserted therein which are operable to lock the fixture to the top nozzle. An arrangement of drive and driven gears connected with a plurality of reaction pins mounted on the base of the fixture are operable to move the fixture base with the top nozzle thereto away from the guide thimbles of the fuel assembly and thereby cause the top nozzle adapter plate to release its connection with the guide thimbles. However, prior to removing the top nozzle, a plurality of stop devices of the fixture are preset and operable for establishing a reference representing the distance between the fixture and work station so that the top nozzle can later be replaced at the same axial position on the fuel assembly it was at before removal.